This disclosure is generally in the field of implantable medical devices. In particular, the disclosure relates to implantable devices for drug release over an extended period.
Implantable devices for the delivery of drugs to patients over extended periods are known. U.S. Pat. No. 5,797,898, U.S. Pat. No. 6,527,762, and U.S. Pat. No. 6,491,666, and U.S. Pat. No. 6,976,982 describe devices for the storage and controlled release of drug formulations from multi-reservoir devices. One category of the devices provide passive controlled release of multiple, individual doses of drug. The reservoirs contain a release system which comprises a drug. That is, the release system of each reservoir can be individually “programmed,” e.g., formulated, to provide selected kinetics of drug release, controlling both the time at which release is initiated and the rate at which the drug is released. Release from different reservoirs can be staggered to provide complex release profiles. Reservoir caps may be provided to close off reservoir openings until such time as release of the drug is desired. Reservoir caps are designed to passively disintegrate or become permeable in vivo to initiate drug release.
It would be desirable to provide improved designs of such implantable devices for therapeutic or prophylactic treatments. It would in particular be desirable to provide small devices for precise, local (e.g., pinpoint) delivery of a drug over an extended period precisely to selected tissue sites, wherein the device has a relatively high drug volume to device volume ratio and can be implanted into a patient by a minimally invasive technique. It would be further desirable to provide devices having a relatively simple design that can be readily fabricated and assembled from relatively few components.